NCERT Solutions for class 7 science chapter 15
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NCERT Solutions for Class 7 Science chapter 15 Exercise Question
Question 1
Fill in the blanks:
(a) An /Pathanto/image that cannot be obtained on a screen is called ___________ .
(b) /Pathanto/image formed by a convex is __________ always virtual and smaller in size.
(c) An /Pathanto/image formed by a __________ mirror is always of the same size as that of the
object.
(d) An /Pathanto/image which can be obtained on a screen is called a __________
/Pathanto/image.
(e) An /Pathanto/image formed by a concave __________ cannot be obtained on a screen.
Answer
(a) An /Pathanto/image that cannot be obtained on a screen is called
virtual /Pathanto/image .
(b) /Pathanto/image formed by a convex is
mirror always virtual and smaller in size.
(c) An /Pathanto/image formed by a
plane mirror is always of the same size as that of the
object.
(d) An /Pathanto/image which can be obtained on a screen is called a
real /Pathanto/image.
(e) An /Pathanto/image formed by a concave
lens cannot be obtained on a screen.
Question 2
Mark âT’ if the statement is true and âFâ if it is
false:
(a) We can obtain an enlarged and erect /Pathanto/image by a convex mirror. (T/F)
(b) A concave lens always form a virtual /Pathanto/image. (T/F)
(c) We can obtain a real, enlarged and inverted /Pathanto/image by a concave mirror. (T/F)
(d) A real /Pathanto/image cannot be obtained on a screen. (T/F)
(e) A concave mirror always form a real /Pathanto/image. (T/F)
Answer
a) False
b) True
c) True
d) False
e) False
Question 3
Match the items given in Column I with one or more items of Column
II
Column I |
Column II |
(a) A plane mirror |
(i) Used as a magnifying glass. |
(b) A convex mirror |
(ii) Can form /Pathanto/image of objects
spread over a large area. |
(c) A convex lens |
(iii) Used by dentists to see
enlarged /Pathanto/image of teeth. |
(d) A concave mirror |
(iv) The /Pathanto/image is always inverted
and magnified. |
(e) A concave lens |
v) The /Pathanto/image is erect and of the
same size as the object |
|
vi) The /Pathanto/image is erect and smaller
in size than the object. |
Answer
Column I |
Column II |
(a) A plane mirror |
v) The /Pathanto/image is erect and of the
same size as the object |
(b) A convex mirror |
(ii) Can form /Pathanto/image of objects
spread over a large area. |
(c) A convex lens |
(i) Used as a magnifying glass. |
(d) A concave mirror |
(iii) Used by dentists to see
enlarged /Pathanto/image of teeth |
(e) A concave lens |
vi) The /Pathanto/image is erect and smaller
in size than the object. |
Question 4
State the characteristics of the /Pathanto/image formed by a plane
mirror.
Answer
(i) Plane mirror forms an erect and virtual /Pathanto/image.
(ii) height of the /Pathanto/image and object are equal.
(iii)Distance of /Pathanto/image and object from mirror are equal.
(iv) /Pathanto/image formed laterally inverted
Question 5
Find out the letters of English alphabet or any other language known
to you in which the /Pathanto/image formed in a plane mirror appears exactly like the letter itself.
Discuss your findings.
Answer
A, H, I, M, O, T, U ,V, W These letter appear same when we seen through a plane mirror
Question 6
What is a virtual /Pathanto/image? Give one situation where a
virtual /Pathanto/image is formed.
Answer
The /Pathanto/image which formed behind the mirror is called virtual /Pathanto/image.These
/Pathanto/image can not obtain on mirror.
Question 7
State two differences between a convex and a concave
lens.
Answer
Concave mirror |
Convax mirror |
(a) real /Pathanto/image formed |
(a) virtual /Pathanto/image formed. |
(b)it formed magnified /Pathanto/image |
(b) it formed diminished |
Question 8
Give one use each of a concave and a convex mirror.
Answer
Concave mirror is used in solar furnaces to conserve sunlight.
Convex mirror is used as side view mirror in vehicles
Question 9
Which type of mirror can form a real /Pathanto/image?
Answer
Concave mirror
Question 10
Which type of lens forms always a virtual
/Pathanto/image?
Answer
Concave lens
Choose the correct option in Questions 11-13:
Question 11
A virtual /Pathanto/image larger than the object can be produced by
a
(i) concave lens (ii) concave mirror (iii) convex mirror (iv) plane mirror
Answer
(ii) concave mirror
Question 12
David is observing his /Pathanto/image in a plane mirror. Die
distance between the mirror and his /Pathanto/image is 4 m. If he moves 1 m towards the mirror, then the
distance between David and his /Pathanto/image will be
(i) 3 m (ii) 5 m (iii) 6 m (iv) 8 m
Answer
(iii) 6 m
Question 13
The rear view mirror of a car is a plane mirror. A driver is
reversing his car at a speed of 2 m/s. The driver sees in his rear mew mirror the /Pathanto/image of a
truck parked behind his car. The speed at which the /Pathanto/image of the truck appears to approach the
driver will be
(i) 1 m/s (ii) 2 m/s (iii) 4 m/s (iv) 8 m/s
Answer
(ii) 4 m/s